JP3792937B2 - Brake control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a brake control device that performs so-called ABS control for controlling brake fluid pressure to prevent a wheel from being locked during braking, and in particular, a disturbance caused by noise superimposed on a wheel speed sensor output or defective mounting. The present invention relates to a processing technique when an abnormality occurs due to the above.
[0002]
[Prior art]
In a brake control device that executes ABS control, a pseudo vehicle speed is estimated from the wheel speed of each wheel, and the brake fluid pressure is reduced, held, and increased based on the pseudo vehicle speed and the wheel speed of each wheel. Pressure is applied to prevent the wheels from locking during braking, so that both steering performance and running stability can be ensured and the braking distance can be shortened.
[0003]
In such a brake control device, the detection accuracy of the wheel speed is important in executing the above-described ABS control, and if an abnormality occurs in the wheel speed sensor, it is difficult to execute normal ABS control. In view of this, there has been proposed an apparatus that detects an abnormality of the wheel speed sensor and executes control corresponding to the abnormality.
[0004]
As such a conventional brake control device, for example, a device described in JP-A-10-147232 is known.
This prior art detects the abnormality of each wheel, and calculates the estimated vehicle speed from the wheel speeds of other wheels excluding the wheel speed of the wheel where the abnormality is detected to the estimated vehicle speed calculation means when the abnormality is detected. An abnormality detecting means for causing the wheel speed calculated in the current control cycle in the same wheel to be greater than the wheel speed calculated in the previous control cycle, exceeding the set value α, and When the estimated vehicle speed (pseudo vehicle speed) exceeds the set value β, the wheel speed calculated in the current control cycle for this wheel is determined to be abnormal. The estimated vehicle body speed is calculated from the wheel speed excluding.
[0005]
Therefore, in this prior art, when noise is superimposed on the output of the wheel speed sensor and the output becomes large, the wheel speed is α or more larger than the previous value and β or more than the estimated vehicle speed. If it is larger, it is determined that there is an abnormality, and this wheel speed is not used for estimating the vehicle speed, and the estimated vehicle speed does not become higher than the actual vehicle speed, thereby executing unnecessary ABS control. Thus, it is possible to prevent a problem that an unnecessary pressure reduction is performed, and an erroneous determination that an abnormality occurs when the wheel speed suddenly returns from a large skid, and an unnecessary pressure reduction due to ABS control can be prevented.
[0006]
[Problems to be solved by the invention]
As described above, in the prior art, when an abnormality such as noise is superimposed on the wheel speed sensor, the vehicle speed is estimated by excluding the abnormal wheel, thereby improving the control accuracy. Although it was possible to measure, the abnormality of the wheel speed sensor was determined by comparing the output value of the wheel speed sensor with the pseudo vehicle speed, and comparing with the previous output value. Could occur.
That is, in forming the pseudo vehicle speed, in the first control cycle when the ABS control is started, each wheel tends to be locked and an accurate wheel speed cannot be obtained. Aside from the device, an inexpensive device that does not have a longitudinal acceleration sensor calculates the value by subtracting a fixed value from the previous pseudo vehicle speed.
Therefore, especially on a low friction coefficient road (hereinafter referred to as a low μ road), the deceleration of the vehicle body speed is low, and the pseudo vehicle body speed Vi obtained by subtracting the fixed value in this way is higher than the actual vehicle body speed. May be lower. On the other hand, when the ABS control for avoiding the lock of the wheel is executed, the wheel speed is once increased to substantially the same value as the actual vehicle speed by the decompression process. If the vehicle speed is higher than the above-described β, there is a risk of erroneous determination as abnormal.
Alternatively, when the driving wheel slips and the wheel speed of the driving wheel becomes higher than the pseudo vehicle speed, there is a possibility that the abnormality is similarly erroneously determined.
[0007]
The present invention has been made paying attention to the above-mentioned problems. When an abnormality such as noise is superimposed on the output of the wheel speed sensor, the pseudo vehicle speed is formed by the wheel speed excluding the abnormal wheel. In a brake control device capable of executing control, it is intended to prevent erroneous determination on a low μ road as described above and erroneous determination due to driving wheel slip, improve abnormality determination accuracy, and improve control quality. .
[0008]
[Means for Solving the Problems]
  In order to achieve the above-mentioned object, as shown in the claim correspondence diagram of FIG. 1, the present invention provides a brake configured to be able to independently reduce the brake hydraulic pressure of the wheel cylinder a that brakes each wheel of the vehicle. Unit b, wheel speed sensor c for detecting the rotational speed of each wheel, and the highest value among outputs from these wheel speed sensors cOn the basis of thePseudo body speedTheThe required pseudo vehicle speed forming means d;SaidABS control means e for performing ABS control for preventing wheel lock during braking by reducing the brake fluid pressure by the brake unit b as necessary based on the difference between the pseudo vehicle speed and each wheel speed;TheIn the equipped brake control device, AWhen executing BS control, DecreaseMeasure pressure timeIn addition, when pressure increase is performed, the pressure reduction time is returned to zero.And an abnormality determining means f for determining that there is an abnormality in the wheel speed sensor having the highest value when the measurement time has passed a predetermined time. The pseudo vehicle body speed forming means d is provided by the abnormality determining means f. When it is determined that there is an abnormality in the output of the wheel speed sensor c, the pseudo vehicle speed is formed based on the output of the wheel speed sensor c excluding the abnormality determination wheel. . Therefore, when an abnormality occurs in the wheel speed sensor c and its output value becomes high, when the ABS control is executed, the output value of the wheel speed sensor c becomes high, so that the pseudo vehicle speed becomes high. Then, pressure reduction is performed on the normal wheel. Normally, when decompression is performed, the wheel speed returns to the pseudo vehicle speed and the decompression is stopped, whereas one output value of the wheel speed sensor c is abnormally high and the pseudo vehicle speed is higher than actual. In the case where it is formed, the wheel speed does not return to the pseudo vehicle body speed, so that the decompression time becomes longer. Therefore, the abnormality determination means f measures the pressure reduction time generated by the increase in the pseudo vehicle speed in this way, and determines that there is an abnormality if this measurement time exceeds a predetermined time. If the abnormality determination is made in this way, the pseudo vehicle speed locking means d forms the pseudo vehicle speed based on the output of the wheel speed sensor c excluding the abnormal wheels. In this way, in the present invention, since abnormality is determined by the decompression time, even when the normal wheel speed exceeds the estimated pseudo vehicle speed in the first cycle of control during braking on a low μ road, only that In this case, it is not determined that there is an abnormality because no decompression is involved. Accordingly, it is possible to improve the control quality by improving the abnormality determination accuracy as compared with the prior art.
  When the abnormality determining means f determines whether or not the pseudo vehicle speed at the start of pressure reduction has increased with respect to the pseudo vehicle speed before decompression, as described in claim 2. It is preferable to continue the measurement of the decompression time, and to return the decompression time to 0 at other times.
[0009]
  Note that the abnormality determination means f is a claim.3As described above, when the output value of the wheel speed sensor c is equal to or lower than a predetermined low speed, it is preferable that the measurement of the decompression time is not performed. That is, in normal ABS control, particularly when the road surface μ changes from a high μ road to a low μ road, a relatively long period of pressure reduction may be performed in a low speed region. By not measuring the decompression time at low speeds or less, normal ABS control is not erroneously determined as a wheel speed sensor abnormality. Claims4As described in, AIt is preferable that the measured value of the decompression time is returned to 0 when the BS control is stopped. Therefore, no abnormality is erroneously determined during normal ABS control.
[0010]
  Claims5As described above, it is preferable that the abnormality determination means f is configured to determine that there is an abnormality when both the pressure reduction time for the front wheels and the pressure reduction time for the rear wheels have passed a predetermined time. That is, when an abnormality occurs in one of the wheel speed sensors c and the pseudo vehicle speed increases from the actual vehicle speed, the decompression process is performed on the remaining normal three wheels during the ABS control. Such an abnormal state can be determined with high accuracy. Claims6As described above, the abnormality determination means f determines that there is an abnormality when the pressure reduction time for the front wheels has passed a predetermined time and the pressure increase time for the rear wheels exceeds a preset value. It is preferable to configure so as to. Therefore, it is possible to prevent the braking posture from being generated only at the rear wheel and the vehicle posture from becoming unstable.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 2 is a configuration diagram showing a main part of the brake device according to the embodiment, in which 1 is a master cylinder. The master cylinder 1 is configured to generate hydraulic pressure when the driver operates a brake pedal (not shown).
[0012]
The master cylinder 1 is connected to a wheel cylinder 3 via a brake circuit 2. In the middle of the brake circuit 2, a pressure increasing state in which the upstream (master cylinder 1 side) and the downstream (wheel cylinder 3 side) of the brake circuit 2 communicate with each other and the brake fluid in the wheel cylinder 3 is released to the drain circuit 4. A switching valve 5 is provided that can be switched between a reduced pressure state and a holding state in which the brake circuit 2 is shut off and the brake fluid pressure of the wheel cylinder 3 is maintained. Therefore, the hydraulic pressure of the wheel cylinder 2 can be arbitrarily controlled based on the switching of the switching valve 5.
[0013]
The drain circuit 4 is provided with a reservoir 6 capable of storing brake fluid. A reflux circuit 8 that connects the reservoir 6 and a position upstream of the switching valve 5 of the brake circuit 2 is provided. In the reflux circuit 8, the brake fluid stored in the reservoir 6 is supplied to the brake circuit 2. A pump 7 for refluxing is provided.
[0014]
The configuration in the range surrounded by the one-dot chain line in FIG. 2 described above is combined into one as the brake unit 11. 2 illustrates the configuration of one wheel, the overall configuration is as shown in FIG. 3, and the brake unit 11 includes four wheel cylinders 3 (FIG. 3) of four wheels FR, FL, RR, RL. The brake fluid pressure is not shown in FIG. Incidentally, the vehicle to which the present embodiment is applied is a rear wheel drive vehicle using the rear wheels RR and RL as drive wheels.
[0015]
The operation of the switching valve 5 and the pump 7 of the brake unit 11 is controlled by the control unit 12. The control unit 12 is provided with wheel speed sensors 13, 13, 13, and 13 that detect the rotational speeds of the wheels FR, FL, RR, and RL as input means.
[0016]
Next, the brake control of this embodiment will be described.
The brake control according to the present embodiment executes so-called ABS control for controlling the brake fluid pressure for each wheel in order to prevent the wheel from being locked during braking. FIG. 4 shows the overall flow.
[0017]
This brake control is performed at a cycle of 10 msec. First, at step S1, the sensor frequency is obtained from the sensor pulse number ND and the cycle TD of each wheel speed sensor 13 generated around 10 msec, and the wheel speed Vw and the wheel acceleration are obtained. ΔVw is calculated. In the following description, when the symbols FR, FL, RR, and RL are added after the symbol Vw, the wheel speed of the wheel is indicated.
[0018]
In step S2, the pseudo vehicle body speed Vi is calculated. This step S2 corresponds to the pseudo vehicle speed forming means in the claims, and details of calculation for obtaining the pseudo vehicle speed Vi will be described later.
In step S3, the vehicle body deceleration ΔV is calculated based on the change rate of the pseudo vehicle body speed Vi.
[0019]
  In step S4, a calculation for obtaining the pressure reduction threshold λ1 is performed. The depressurization threshold λ1 is such that the wheel speed Vw is the value λ1Is a value at which decompression is performed, for example, based on the selected wheel speed Vfs which is the highest value among the wheel speeds of four wheels.The pseudo vehicle speed Vi is calculated, and the pseudo vehicle speed Vi is calculated.Based on the following formula,
λ1 = A ・Vi-B
In the above equation, A and B are arbitrary coefficients, and the decompression threshold λ1 isPseudo body speed ViThe value is set to a value that is a little lower than that, and is a slip ratio suitable for obtaining a braking force.
[0020]
In step S5, it is determined whether or not the wheel speed Vw is lower than the depressurization threshold λ1, and if it is lower than the depressurization threshold λ1, the process proceeds to step S7, and the switching valve 5 is switched to the depressurized state and the wheel cylinder pressure is increased. Execute decompression control to decompress. In this case, the process further proceeds to step S12, and the output of the ABS control signal AS indicating that the ABS control is being executed is set to 150.
[0021]
If NO is determined in step S5 (when Vw> λ1), the process proceeds to step S6 to determine whether or not the wheel acceleration ΔVw is less than a preset holding threshold, and is greater than the holding threshold. In this case, it is determined that the wheel speed has been restored, and the process proceeds to step S8 to perform pressure increase control (switching the switching valve 5 to a pressure increasing state). On the other hand, if the wheel speed is less than the holding threshold value, the process proceeds to step S9. Switch to the hold state. The output to the switching valve 5 in the pressure increasing control and holding control in these steps S8 and S9 is also made in step S10.
[0022]
In each control of steps S7 to S9, the command time TGEN, TZOU of each control is set, and the control signal is actually output to the switching valve 5 in the valve output process of step S10.
[0023]
In step S11, it is determined whether or not 10 ms has elapsed. When 10 ms has elapsed, the count of the timer AS of the ABS control signal is decremented by 1 in step S13.
[0024]
Next, the flow of the pseudo vehicle speed calculation process in step S2 will be described with reference to the flowchart of FIG.
First, in step 100, an abnormality counter KDECTFR for the right front wheel, which will be described later, exceeds an abnormality determination decompression time TG, an abnormality counter KDECTFL for the left front wheel exceeds an abnormality determination decompression time TG, and the pressure increase counter CONTAMODE is set to a set value Y. If the condition is satisfied, the process proceeds to step 103. If the condition is not satisfied, the process proceeds to step 101.
In step 101, it is determined whether or not the right front wheel abnormality counter KDECTFR exceeds the abnormality determination decompression time TG and the rear wheel abnormality counter KDECTR exceeds the abnormality determination decompression time TG, and this condition is satisfied. If yes, go to Step 103. If not, go to Step 102. Further, in step 102, it is determined whether or not the abnormality counter KDECTFL for the left front wheel exceeds the abnormality determination decompression time TG and the abnormality counter KDECTR for the rear wheel exceeds the abnormality determination decompression time TG, and this condition is satisfied. If YES in step 103, the flow advances to step 103. If this condition is not satisfied, the flow advances to step 104.
In step 103, which proceeds when any of the conditions of steps 100, 101, and 102 is satisfied, processing for setting the abnormality confirmation signal SVW_AB (set to 1) is performed.
[0025]
If the abnormality confirmation signal SVW_AB is set (abnormality has occurred) based on the processing in steps 100 to 103, the selected wheel speed Vfs is set to the third wheel speed among the four wheel speeds in step 105. On the other hand, if the abnormality confirmation signal SVW_AB is not set (normally when no abnormality has occurred), the selected wheel speed Vfs is selected from the four wheel speeds Vw in step 106. The process of setting the highest value maxVw is performed. That is, at the time of occurrence of abnormality, the selected wheel speed Vfs is formed at step 105, and at the time of normality, the selected wheel speed Vfs is formed at step 106.
[0026]
  Subsequently, in step 107, it is determined whether or not the abnormality confirmation signal SVW_AB has not been formed at the previous control timing, but has been formed at the current control timing. The routine proceeds to 108, where the pseudo vehicle speed Vi is set to the selected wheel speed Vfs. On the other hand, when the abnormality confirmation signal SVW_AB is not first formed at the current control timing in step 107, the process of step 108 is also performed. After the execution, the routine proceeds to step 109 where the pseudo vehicle speed Vi is the selected wheel speed V.fsIf Vi> Vfs, the wheel speed is being decelerated and the routine proceeds to step 110 where the pseudo vehicle speed Vi = Vi−ΔV is processed. ΔV is an estimated vehicle deceleration value and is estimated from the rate of change of the pseudo vehicle body speed Vi. On the other hand, if NO at Step 109, that is, if Vi ≦ Vfs, the wheel speed is being restored, and the routine proceeds to Step 111, where the pseudo vehicle speed Vi is obtained from Vi + z. Note that z is a preset acceleration limiter value. Thereafter, in steps 112 and 113, the abnormality confirmation signal SVW_AB is reset when the output of the ABS control signal is stopped.
[0027]
Next, the valve output process in step S10 will be described in detail with reference to the flowchart of FIG.
First, in steps 201 and 202, it is determined whether or not a pressure reduction command or a pressure increase command has been issued. If a pressure reduction command has been issued, the process proceeds to step 203, and if a pressure increase command has been issued. Proceed to step 207a. If neither the pressure reduction command nor the pressure increase command is made, the process proceeds to step 210a.
[0028]
In step 203, when the pressure reduction command is issued, the pressure increase counter ZOUCNT is reset to 0, and in the subsequent step 203b, the pressure increase counter CONTAMODE = 0 indicating that pressure increase is performed is performed. Further, in step 204, processing for setting the abnormality counter KDECT = KDECT + TGEN is performed. Next, in steps 205 and 206, processing for setting the output port to a reduced pressure is executed until the count value of the reduced pressure counter GENCNT exceeds the reduced pressure command value TGEN. When the pressure reduction command value TGEN exceeds the count value of the pressure reduction counter GENCNT, the process proceeds to step 210.
[0029]
  On the other hand, in step 207a that proceeds when the pressure increase command is issued, the pressure increase counter CONTAMODE is incremented, and in step 207b, the pressure decrease counter GENCNT and the abnormality counter KDECT are reset to 0, and the subsequent steps 208 and 209 increase. The process of setting the output port to increase pressure is executed until the count value of the pressure counter ZOUCNT exceeds the pressure increase command value TZOU. In addition,IncreasePressure command value TZOUButIncreaseWhen the count value of the pressure counter ZOUCNT is exceeded, the routine proceeds to step 210.
[0030]
  If neither the pressure reducing command nor the pressure increasing command is issued, step 210 is performed.aIn step S210, the pressure increase counter CONTAMODE is cleared, the process proceeds to step 210b, the pressure reduction counter GENCNT and the pressure increase counter ZOUCNT are reset to 0, and in step 211, the output port is set to hold. The above steps 201 to 211 are a flow of processing for controlling each state for the command time determined in steps S7 to S9.
[0031]
In step 212, it is determined whether or not the ABS control signal AS is set. If it is set, the process proceeds to step 213. If it is not set, the process proceeds to step 215.
[0032]
In step 213, which proceeds when the ABS control signal AS is set, whether the value obtained by subtracting the previous (10ms before) pseudo vehicle speed Vi from the current pseudo vehicle speed Vi is positive, that is, whether acceleration is in progress. It is determined whether or not the vehicle is accelerating, the acceleration flag FVII is set to 1.
[0033]
In subsequent steps 216 and 217, processing for setting the abnormality counter KDECT to 0 is executed when the acceleration flag FVII is not set or the wheel speed Vw is 0 km / h.
[0034]
That is, the abnormality counter KDECT, which is the basis for the abnormality determination executed in steps 101 and 102 in FIG. 5, is performed in the valve output processing in steps 201 to 217 described above, and an ABS control signal is being output. (AS = 0), AS = 0 is switched to AS ≠ 0, and there is an acceleration of the pseudo vehicle speed Vi (FVII = 1), and the wheel speed Vw of the own wheel is 0 km / h. Higher than that and the vehicle is depressurizing, the abnormal counter KDECT is counted, and on the other hand, the ABS control signal is not output (AS ≠ 0) or the wheel speed Vw of the vehicle Is 0 km / h, or when the own wheel is pressurized (CONTAMODE = 0), the abnormal counter KDECT is cleared.
[0035]
Next, an operation example of the embodiment will be described based on the time charts of FIGS.
The time chart of FIG. 7 shows a control example for the right front wheel in the case of normal control in which no abnormality has occurred in the wheel speed sensor 13, and in this case, braking is performed due to a low μ road or the like. Since the wheel speed VwFR of the right front wheel has greatly decreased at the start, the pressure is reduced by the ABS control, and when the wheel speed Vw is restored by this pressure reduction, the wheel speed VwFR is larger than the pseudo vehicle speed Vi.
[0036]
When the wheel speed Vw is larger than the pseudo vehicle speed Vi in this manner, there is a risk that it has been conventionally determined to be abnormal. In this embodiment, however, the abnormality counter KDECT, which is the basis for abnormality determination, is an ABS control. When the decompression is executed, the count is performed only for one decompression process. Furthermore, after the ABS control signal AS is set, the pseudo vehicle speed Vi is increased and accelerated. If the flag FVII is not set, it is cleared during one process.
[0037]
Therefore, in this embodiment, in such a normal operation of the ABS, the abnormality counter KDECT is not counted over a plurality of control periods, and the count value does not exceed the abnormality determination decompression time TG. Therefore, it is not erroneously determined as abnormal.
[0038]
The time chart of FIG. 8 shows a case where an abnormality has occurred in the wheel speed sensor 13 of the rear wheel during constant speed traveling before deceleration and one of the wheel speeds VwRR and VwRL of the rear wheel has increased significantly. . In this case, the select wheel speed Vfs increases due to the sensor abnormality, and the pseudo vehicle speed Vi increases accordingly.
Thus, when the pseudo vehicle speed Vi increases, the wheel speeds VwFR and VwFL of the front wheels, which are normal wheels, become significantly lower than the pseudo vehicle speed Vi, and as a result, ABS control is started for these front wheels ( Output of ABS control in-progress signal is started). In this case, as a result of setting the acceleration flag FVII in the flow of steps 212 → 213 → 214 in the flowchart of FIG. 6 simultaneously with the start of the ABS control, the process does not proceed from step 216 to step 217, and therefore decompression is executed. Thus, the abnormality counter KDECT counted in steps 201 → 203 → 203b → 204 is not cleared, and is counted over a plurality of control periods. As shown in the time chart of FIG. The count value increases. When the count value of the front wheel exceeds the abnormality determination decompression time TG, the count value of the pressure increase counter CONTAMODE exceeds the set value Y, or the count value of the abnormality counter KDECT for both the front and rear wheels is equal to the abnormality determination decompression time TG. If it exceeds, YES is determined in any one of steps 100 to 102, and the abnormality confirmation signal SVW_AB is set. Therefore, the select wheel speed Vfs is formed by three wheels excluding abnormal wheels, and the pseudo vehicle speed Vi is formed based on the select wheel speed Vfs.
[0039]
As described above, in the present embodiment, it is determined whether or not an abnormality has occurred in the wheel speed sensor 13 as a result of the decompression time of the own wheel being executed after the pseudo vehicle speed Vi is once increased during the ABS control. In addition, the time count is executed when the pressure is increased, the ABS control is stopped, or the wheel speed Vw decreases to 0 km / h. As in the case where the control is executed, it is determined that the sensor is abnormal even if the wheel speed returned from the locked state by the pressure reduction becomes larger than the pseudo vehicle speed Vi calculated based on the change rate ΔVi of the pseudo vehicle speed. Therefore, it is possible to improve the control quality by improving the abnormality determination accuracy.
Similarly, when the drive wheel slips and the wheel speed Vw exceeds the pseudo vehicle speed Vi, the abnormal counter KDECT is not counted, and therefore, it is not determined that there is an abnormality. Similarly to the above, it is possible to improve the control quality by improving the abnormality determination accuracy.
In addition, as described above, when the wheel speed Vw is 0 km / h, the abnormality counter KDECT is cleared, so that the traveling road surface changes from the high μ road to the low μ road during braking, and the decompression time immediately before the stop is reached. Even if an operation based on the normal operation of the ABS that is long is performed, this is not erroneously determined to be abnormal.
Further, in the present embodiment, as shown in step 100 of FIG. 5, the count value of the abnormality counter KDECT for the front wheels exceeds the abnormality determination decompression time TG, and the pressure increase time for the rear wheels exceeds the set value Y. Therefore, the vehicle posture can be stabilized by shortening the time during which only the rear wheel is pressurized and the vehicle posture becomes unstable.
[0040]
As mentioned above, although embodiment was described with drawing, this invention is not limited to this embodiment.
For example, in the embodiment, an example in which the predetermined low speed is set to 0 km / h in clearing the count value of the abnormality counter KDECT when the output value of the wheel speed sensor 13 is equal to or lower than the predetermined low speed is shown. For example, a low speed such as 10 km / h or 5 km / h may be used.
2 shows a configuration in which the wheel cylinder 3 is depressurized / held / increased by one switching valve 5. However, in place of the switching valve 5, the normally open two-position switching that can open and close the brake circuit 2 is shown. An inflow valve and a normally closed two-position switching outflow valve capable of opening and closing the drain circuit 4 may be used.
[0041]
【The invention's effect】
As described above, according to the first to fourth aspects of the present invention, during the ABS control, the decompression time when the decompression is executed as the pseudo vehicle body speed increases is measured, and this measurement is performed. Since it is determined that there is an abnormality when the predetermined time elapses, the value of the normal wheel speed exceeds the pseudo vehicle speed estimated in the first cycle of control when braking on a low μ road. However, since no deceleration is made, it is not determined that there is an abnormality, and if an abnormality occurs in the wheel speed sensor, this abnormality is detected during ABS control, and the sensor is detected during ABS control. It is possible to prevent an adverse effect due to an abnormality, so that it is possible to improve the abnormality determination accuracy and improve the control quality as compared with the prior art.
Further, the invention according to claim 2 or 3 can prevent erroneous determination of normal ABS control as an abnormality of the wheel speed sensor, thereby improving control quality.
The invention according to claim 4 can improve the determination accuracy of occurrence of abnormality.
The invention according to claim 5 can prevent the vehicle posture from becoming unstable.
[Brief description of the drawings]
FIG. 1 is a diagram corresponding to a claim showing a brake control device of the present invention.
FIG. 2 is a hydraulic circuit diagram showing a main part of the embodiment.
FIG. 3 is an overall view of the embodiment.
FIG. 4 is a flowchart showing a flow of ABS control according to the embodiment.
FIG. 5 is a flowchart showing a flow of pseudo vehicle speed calculation according to the embodiment.
FIG. 6 is a flowchart showing a flow of rear wheel valve output processing in the embodiment;
FIG. 7 is a flowchart showing an operation example when the wheel speed sensor of the embodiment is normal.
FIG. 8 is a flowchart showing an operation example when the wheel speed sensor is abnormal in the embodiment;
[Explanation of symbols]
a Wheel cylinder
b Brake unit
c Wheel speed sensor
d Pseudo vehicle body speed forming means
e ABS control means
f Abnormality judgment means
1 Master cylinder
2 Brake circuit
3 Wheel cylinder
4 Drain circuit
5 Switching valve
6 Reservoir
7 Pump
8 Reflux circuit
11 Brake unit
12 Control unit
13 Wheel speed sensor

Claims (6)

A brake unit configured to be able to independently reduce the brake fluid pressure of a wheel cylinder that brakes each wheel of the vehicle;
A wheel speed sensor for detecting the rotational speed of each wheel, and a pseudo vehicle speed forming means for obtaining a pseudo vehicle speed based on the highest value among the outputs of the wheel speed sensors;
ABS control means for executing ABS control for preventing wheel lock at the time of braking by reducing the brake fluid pressure by a brake unit based on the difference between the pseudo vehicle body speed and each wheel speed, if necessary;
In a brake control device comprising:
During execution of the ABS control, as well as measuring the pressure reduction time at which the reduced pressure is performed, to return to 0 the decompression time when the pressure increasing is performed, when the measured time has exceeded the predetermined time An abnormality determination means for determining that the wheel speed sensor having the highest value is abnormal is provided,
When the abnormality determining means determines that the output of the wheel speed sensor is abnormal, the pseudo vehicle speed forming means forms a pseudo vehicle speed based on the output of the wheel speed sensor excluding the abnormality determining wheel. A brake control device configured to perform the above. The abnormality determination means determines whether or not the pseudo vehicle speed at the start of pressure reduction has increased with respect to the pseudo vehicle speed before pressure reduction. 2. The brake control device according to claim 1, wherein the pressure reducing time is returned to 0 at the time of 3. The brake control device according to claim 1, wherein the abnormality determination unit is configured not to perform the measurement of the pressure reduction time when an output value of a wheel speed sensor becomes a predetermined low speed or less. . The abnormality determining means, A BS when the control is stopped, the brake control apparatus according to 3 any one claims 1, characterized in that the measured value of the pressure reducing time is configured to return to the 0 . The abnormality determination means is configured to determine that there is an abnormality when both the decompression time for the front wheels and the decompression time for the rear wheels have passed a predetermined time . brake control apparatus described in one. The abnormality determination means is configured to determine that there is an abnormality when the pressure reduction time for the front wheel has passed a predetermined time and the pressure increase time for the rear wheel exceeds a preset set value. claims 1, characterized in to the brake control apparatus described in 5 any one.

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